1. Field of the Invention
The present invention relates to a resist composition capable of changing in the properties by undergoing a reaction upon irradiation of actinic rays or radiation (e.g., electron beam, X-ray, EUV, UV), a compound for use in the resist composition and a pattern forming method using the resist composition. More specifically, the present invention relates to a resist composition for use in the process of producing a semiconductor such as IC, in the production of a circuit board for liquid crystal, thermal head and the like, in other photofabrication processes, or in a lithographic printing plate or an acid-curable composition, and also relates to a compound for use in the resist composition and a pattern forming method using the resist composition.
2. Background Art
A chemical amplification resist composition is a pattern forming material of forming a pattern on a substrate by producing an acid in the exposed part upon irradiation of radiation such as far ultraviolet light, and changing the solubility in a developer of the part irradiated with actinic radiation and the non-irradiated part resulting from a reaction using the generated acid as the catalyst.
In the case of using a KrF excimer laser as the exposure light source, a good pattern with high sensitivity and high resolution is formed because a resin exhibiting small absorption mainly in the 248-nm region and having poly(hydroxystyrene) as the basic skeleton is used as the main component, and this is a good system as compared with the conventional naphthoquinone diazide/novolak resin system.
On the other hand, in the case where a light source at a shorter wavelength, for example, an ArF excimer laser (193 nm) is used as the exposure light source, even the above-described chemical amplification system is not satisfied because the compound having an aromatic group inherently exhibits large absorption in the 193-nm region.
Therefore, development of a resist for an ArF excimer laser, containing a resin having an alicyclic hydrocarbon structure, is proceeding.
As for the acid generator which is a principal constituent component of the chemical amplification resist, a triphenylsulfonium salt is generally known (see, for example, Patent Document 1: U.S. Pat. No. 6,548,221).
However, this acid generator still has many insufficient points, and a resist composition enhanced in the sensitivity and the like is demanded.
Also, in the case of using a light source of emitting an electron beam, X-ray, EUV or the like, the exposure is performed in a vacuum and therefore, the outgas problem that a low boiling point compound such as solvent or a resist material decomposed due to high energy volatizes and contaminates the exposure apparatus, becomes important. Various studies are recently proceeding for the reduction of the outgas and various techniques have been attempted, for example, a technique of providing a topcoat layer to suppress the volatilization of a low molecular compound (see, for example, Patent Document 2: European Patent 1,480,078) or a technique of adding a radical trapping agent for suppressing the decomposition of a polymer (see, for example, Patent Document 3: U.S. Pat. No. 6,680,157). Thus, effort for reducing the outgas is demanded also in terms of the acid generator.
In Patent Documents 4 and 5 (JP-A-2003-149800 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) and JP-A-2004-4557) or the like, a new acid generator is introduced.
On the other hand, a case of using a sulfonium salt having a specific structure in a photopolymerization composition containing an epoxy compound or the like is introduced in Patent Document 6: U.S. Pat. No. 4,694,029.